Conventional processes for preparing ethylene glycol (EG) and propylene glycol (PG) entail partial oxidation of ethylene or propylene followed by hydration of the resulting epoxides. More recently, hydrogenation of glycolate or oxalate esters has been proposed as alternative methods for preparing EG from alternative feedstock materials. These latter methods, however, suffer from one or more drawbacks, such as requiring the use of expensive precious or rare metal catalysts, high temperatures, and/or high hydrogen pressures.
Thus, there is a need in the art for a process for hydrogenating α-functional esters (such as glycolate esters, lactate esters, and oxalate esters) that does not suffer from these drawbacks.
The present invention addresses this need as well as others, which will become apparent from the following description and the appended claims.